CVE-2026-34734: HDF5: H5T__conv_struct Use After Free

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-09 · updated 2026-10-26
Weakness: CWE-416

Description

HDF5 is software for managing data. In 1.14.1-2 and earlier, a heap-use-after-free was found in the h5dump helper utility. An attacker who can supply a malicious h5 file can trigger a heap use-after-free. The freed object is referenced in a memmove call from H5T__conv_struct. The original object was allocated by H5D__typeinfo_init_phase3 and freed by H5D__typeinfo_term.

Affected products

HDF5: before 1.14.1-2 — fixed in 1.14.1-2

How to fix

Upgrade to a fixed version: HDF5 1.14.1-2. Check the vendor advisory for mitigations.

References

https://github.com/HDFGroup/hdf5/security/advisories/GHSA-w7v2-9cmr-pwwj
https://access.redhat.com/security/cve/CVE-2026-34734
https://bugzilla.redhat.com/show_bug.cgi?id=2457034
https://github.com/HDFGroup/hdf5/security/advisories/GHSA-w7v2-9cmr-pwwj
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34734.json

Get alerted when CVE-2026-34734 or the next vulnerability affects your stack